Make ActiveRecord ConnectionPool.connections thread-safe.
#36473
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ConnectionPool documentation is clear on the need to synchronize access to @connections but also states that public methods do not require synchronization. Existing code exposed @connections directly via attr_reader. The fix uses synchronize() to lock @connections then returns a copy to the caller using Array.dup(). Includes comments on the connections method that thread-safe access to the connections array does not imply thread-safety of accessing methods on the actual connections. Adds a test-case that modifies the pool using a supported method in one thread while a second thread accesses pool.connections. The test fails without this patch. Fixes rails#36465.
rafaelfranca
requested changes
Jun 13, 2019
Co-Authored-By: Rafael França <rafaelmfranca@gmail.com>
rafaelfranca
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Jun 13, 2019
rafaelfranca
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Jun 13, 2019
* Make ActiveRecord `ConnectionPool.connections` thread-safe. ConnectionPool documentation is clear on the need to synchronize access to @connections but also states that public methods do not require synchronization. Existing code exposed @connections directly via attr_reader. The fix uses synchronize() to lock @connections then returns a copy to the caller using Array.dup(). Includes comments on the connections method that thread-safe access to the connections array does not imply thread-safety of accessing methods on the actual connections. Adds a test-case that modifies the pool using a supported method in one thread while a second thread accesses pool.connections. The test fails without this patch. Fixes #36465. * Update activerecord/test/cases/connection_pool_test.rb [jeffdoering + Rafael Mendonça França]
rafaelfranca
pushed a commit
that referenced
this pull request
Jun 13, 2019
* Make ActiveRecord `ConnectionPool.connections` thread-safe. ConnectionPool documentation is clear on the need to synchronize access to @connections but also states that public methods do not require synchronization. Existing code exposed @connections directly via attr_reader. The fix uses synchronize() to lock @connections then returns a copy to the caller using Array.dup(). Includes comments on the connections method that thread-safe access to the connections array does not imply thread-safety of accessing methods on the actual connections. Adds a test-case that modifies the pool using a supported method in one thread while a second thread accesses pool.connections. The test fails without this patch. Fixes #36465. * Update activerecord/test/cases/connection_pool_test.rb [jeffdoering + Rafael Mendonça França]
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ConnectionPool documentation is clear on the need to synchronize
access to @connections but also states that public methods do not
require synchronization. Existing code exposed @connections
directly via attr_reader. The fix uses synchronize() to lock
@connections then returns a copy to the caller using Array.dup().
Includes comments on the connections method that thread-safe access
to the connections array does not imply thread-safety of accessing
methods on the actual connections.
Adds a test-case that modifies the pool using a supported method
in one thread while a second thread accesses pool.connections.
The test fails without this patch.
Fixes #36465.
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